Punch head assemblies for use in turret punch presses must be periodically reconfigured for a variety of reasons. When the punch tool becomes dull, it must be sharpened. However, such sharpening reduces the height of the punch tool. As a consequence, the punch tool height must be adjusted. Moreover, periodically, a replacement tool is substituted for the punch tool. This requires the changing of the stripper plate for one having a different hole configuration which will match the hole shape of the replacement tool.
Various attempts have been made in the prior art to provide for punch tool height adjustment. Chief among these prior art patents are U.S. Pat. Nos. 5,329,835, 4,375,774, and 5,131,303. U.S. Pat. No. 5,329,835 to Timp et al is directed to incremental adjustment of the punch within the punch housing using a plurality of detents and detent stops. The punch is rotatable in 15.degree. increments resulting in 0.004 inch punch depth adjustment increments. U.S. Pat. No. 4,375,774 to Wilson et al is directed to an adjustable depth punch tip which is keyed by two key pathways 90.degree. apart from each other and operatively interacting with a key affixed to the punch driver. U.S. Pat. No. 5,131,303 to Wilson et al is directed to an adjustable punch assembly in which a wire clip engages equiangular detents for incremental adjustment of the punch tip relative to the punch assembly.
In addition, various prior art components have been provided to permit adjustment between components. U.S. Pat. No. 583,908 to Kenyon discloses a nut lock comprising two ball bearings, biased together between two springs. In the normal position, the ball bearings are directly over the axis of the nut and engage the threads, thus locking the nut from rotation. By inserting a pin through a hole in the nut, the ball bearings are pushed apart and disengaged from the thread, allowing rotation of the nut or threaded portion. U.S. Pat. No. 3,829,816 to Barry et al shows a one-way clutch which is used in connecting drill pipe sections. The clutch is made up of a single roller biased by a spring and a cam surface. U.S. Pat. No. 1,386,259 to Jourdan et al is directed to a nut fastener in which a ball is interposed between the nut and bolt in a cavity formed between the nut and bolt. U.S. Pat. No. 1,383,414 to Mansell shows a locking nut with a channel in which a plunger having a locking disk is mounted. U.S. Pat. No. 1,334,389 to Murray shows a self-locking nut having an eccentric recess in which a roller is spring-biased so as to engage the bolt. A tool is required to displace the roller against the spring so as to disengage the lock nut from the bolt. U.S. Pat. No. 5,146,832 to Wilson et al shows deformable tabs for holding a punch tip in place.
With respect to stripper plates, the prior art contemplates various release mechanisms. U.S. Pat. No. 4,248,111 to Wilson et al shows a stripper plate release mechanism in which clip tabs having holding tabs engage a groove in the stripper plate. A separate fork-shaped tool slides into a groove and forces the clip tabs outwardly, thereby disengaging the holding tabs. U.S. Pat. No. 5,301,580 to Rosene et al discloses a locking ring stripper plate assembly comprising a rotatable stripper plate cap which can be manually rotated with respect to a guide sleeve. The stripper plate is released by rotating a cap to loosen a split end retaining wire. A spring-loaded locking button locks the rotatable stripper cap in position. U.S. Pat. No. 3,521,911 to Hanes et al shows an expandable split latch ring mounted on one pipe section and received in a groove in an adjacent pipe section, with the latch ring engaged and disengaged using a malleable lock. U.S. Pat. No. 5,127,293 to Chatham shows a stripper plate which is held in place by a retaining ring which has locator slots and retaining projections and hence is keyed for released and locked operation. U.S. Pat. No. 4,446,767 to Wilson shows a stripper plate held in place by a split locking ring. U.S. Pat. No. 4,092,888 to Wilson shows a stripper plate held in place by a resilient retaining ring. U.S. Pat. Nos. 4,989,484, 5,056,392 and 5,081,891 to Johnson et al, each show a quick release mechanism for a stripper plate in which a spring-biased locking ring rotates to engage or disengage pins on the stripper plate which has pin receiving slots. U.S. Pat. No. 2,491,128 to Nelson shows a buffer employing a wedge block to expand a split ring.
All of the prior art references have the limitation that incremental adjustment (rather than infinite adjustment) of the punch tool height is achieved. Moreover, none of the prior art references permits a quick release of the stripper plate without major disassembly of the punch tool assembly. The present invention addresses these disadvantages.